Two medical experts are expected to give starkly different testimony in the trial to determine whether Sumner Redstone has the capacity to make decisions about his health care and if he is unduly influenced by those around him.

So far, only one of them has been heard: Dr. Stephen L. Read.

Read is a geriatric psychiatrist who was hired by Redstone’s former companion Manuela Herzer to evaluate the mogul’s mental state following her ejection from his home last fall.

Read's testimony was highly technical, but, in short, he believes Redstone has moderate dementia and was impaired when he made the decision to give Herzer the boot.

Read described Redstone as a “very, very thin shadow of what he was” and said, “It was very sad to see how much he didn’t understand about his life.”

Read also said he suspects Redstone suffers from Progressive Supranuclear Palsy and a brain ischemia, which is a shortage of blood flow to the organ.

These conditions, said Read, could explain why Redstone didn’t hesitate to sever a decadeslong relationship with Herzer.

“Mr. Redstone has a propensity now to erupt in anger,” said Read. “When anger takes over, reasoning is ablated. That removes his inability to think about this, access memory, consider alternatives … to do the things that are required to make an informed decision.”

While evaluating Redstone, Read said he needed to adapt his test to compensate for the mogul’s physical difficulties.

“Mr. Redstone can’t hold a pencil,” said Read. “He’s completely disabled. For the most basic acts of a human’s life, he can’t do them himself.”

Read believes Redstone also could suffer from delusions, which Herzer’s attorney, Pierce O’Donnell, said explains why the mogul holds false beliefs about his client, despite evidence to the contrary.

After the lunch recess, Redstone's attorney, Robert Klieger, cross-examined Read. He pointed out that Read’s evaluation of Redstone’s capacity was based on that required to execute a contract, which is on the high end of the spectrum. He asked Read what’s at the low end.

“In my experience, the lowest standard is the decision to marry or divorce,” said Read.

Klieger then rhetorically asked, “A decision to sever a relationship with someone requires the lowest level of capacity?”

Point Klieger.

Read agreed that if the relationship between Redstone and Herzer had been severed, “it would be rational for her to not be the health-care agent.”

On the subject of delusions, Klieger asked whether an incident in which Herzer allegedly intercepted a letter to Redstone from his ex-girlfriend Sydney Holland and created a fake one to give him instead struck Read as delusional because he didn’t find it plausible enough to have happened.

Read said that if the court decides the incident happened, then Redstone’s perception of it happening would not be a delusion.

The bottom line: Read accepted Herzer’s accounts as truthful while assessing Redstone, and if the court finds that she’s lying, then Read's assessment of the mogul’s mental health could be moot.

One notable moment in Klieger’s line of questioning was his admission that Redstone has a feeding tube. “Because of Mr. Redstone’s problem swallowing, he cannot eat,” he said.

But the most important answer was likely the last. Klieger asked Read, after everything that has happened since October and everything he’s heard today, if it would be practical for Herzer to be Redstone’s health-care agent.

“It would be a very difficult role for her to undertake at this time,” said Read.

This is just one opinion of Redstone’s medical state. His team’s medical expert, Dr. James Spar, also will testify during the trial. Several nurses who care for the mogul also are expected to take the stand.

May 6, 3:05 p.m. Updated with Robert Klieger's cross-examination of Dr. Stephen Read.